Species textHistorically, this species is subject to large fluctuations in abundance. Its current situation in the county (2011) appears perilous, being restricted mainly to coastal sites, occasional singles being found up to a few miles inland. The most recent records from the north of the county come from the large nature reserves either side of the Colne estuary, but sightings are rare. The Wall now seems absent from the Dengie sea wall but sightings still occur further west along the Crouch and it is probably under-recorded towards Foulness. Its stronghold is Canvey Island and the post-industrial sites along the Thames centred around Tilbury extending as far west as Rainham Marshes. Butterfly Conservation evidence in the region points to climate change producing a shift in phenology, producing a (partial) 3-brooded life-cycle along the Thames whilst a generally 2-brooded phenology remains in the Cambridgeshire Fens and in Northern England. Small, isolated colonies inland have therefore declined, being consistently 'caught' between broods and being exposed to high winter mortality, not having the dual hibernation outlet of the Speckled Wood, a close cousin with a corresponding upward trend. Hope comes from the South Coast counties, where some gains have been made inland in the last 2 years. But in Essex at present, only large or well-connected primary habitats seem capable of holding small, viable colonies. (Butterfly Conservation, Cambridgeshire & Essex branch Newsletters 2009 & 2011: Rob Smith & Louise Bacon) References